1. Field of the Invention
The present invention relates to a sheet-like material guiding device of an offset printing press.
2. Description of the Related Art
This type of device is disclosed, for example, in Japanese Unexamined Patent Publication No.4-211943. This publication discloses a sheet-fed offset printing press which delivers a printed sheet from a printing unit to a sheet pile device through a delivery passage defined between a chain towing transport mechanism and a transport guide mechanism; wherein the transport guide mechanism is composed of a transport belt (tape) extending in a direction of transport (circumferential direction), and being revolvingly driven in synchronism with the chain towing transport mechanism. The transport belt is connected to a suction wheel (vacuum wheel), and is movable in the transport direction in a manner interlocked with the suction wheel which is movable in the transport direction in accordance with a change in paper size. Elimination of loosening of the transport belt during its motion toward a loose side has been performed by a plumb bob interposed halfway in a looping of the transport belt.
As described above, while the transport belt is moving toward a loose side during the movement of the suction wheel, elimination of loosening of the transport belt has been performed by a plumb bob interposed halfway in a looping of the transport belt. As a result, the tension of the transport belt becomes, as such, a load on the movement of the suction wheel. Thus, a great power is required for the movement of the suction wheel. That is, a power source enough powerful to overcome the weight of the plumb bob is needed, thereby inducing a cost increase. Furthermore, during the movement of the suction wheel, the transport belt may be stretched by the plumb bob, causing a change in the tension. If the plumb bob happens to be inclined, the transport belt may be loosened.